Anesthesiologists looking to achieve good needle visualization at steeper angles of insertion may get better results using echogenic needles with beam steering versus using these technologies individually, new research suggests.
“Needle visualization is of utmost importance when providing regional anesthesia care and to provide a safe and efficacious block,” said Christopher Prabhakar, MD, lead study author and clinical instructor in the Department of Anesthesiology, Pharmacology and Therapeutics at the University of British Columbia, in Vancouver.
Echogenic needles use coatings or notchings to increase the amount of ultrasound beams that get bounced back, while beam steering “angles the beam of the ultrasound transducer to provide a more perpendicular angle with respect to the needle that is inserted,” Dr. Prabhakar said. Although both technologies can improve visualization, there is “no appreciation for what is the best technology to use at moderate angles of insertion between 40 to 60 degrees,” the researchers wrote. They conducted the study to determine whether beam steering will improve visibility when used with echogenic (Pajunk SonoPlex Stim 22 gauge, 80 mm) and nonechogenic (Pajunk UniPlex NanoLine 22 gauge, 80 mm) needles within that range.
“We looked at steeper angles of insertion at 40, 50 and 60 degrees to see whether either of those technologies or the combination of those technologies were preferable to improve needle visualization,” Dr. Prabhakar said.
The researchers had an experienced regional anesthesiologist insert the needles individually into uncooked pork loin using ultrasound guidance and then took three ultrasound still images at each angle (without beam steering, moderate beam steering and steep beam steering). The images were then shown to 20 participants including consultant anesthesiologists or anesthesia residents who had completed a one-month rotation in regional anesthesia. Participants were blinded to the needle type and whether beam steering was used, and were asked to grade needle visibility on a scale of 0 to 10. The scores were separated into three categories: poor (0-3.3), intermediate (3.4-6.6) and good (6.7-10).
The researchers found that beam steering boosted visibility for both needle types at 40 degrees, but was less useful beyond that for nonechogenic needles.
“At 40 degrees both echogenic and nonechogenic were improved with beam steer technology, particularly steep beam steer,” Dr. Prabhakar said. “Whereas in 50 and 60 degrees, the echogenic needles were superior to nonechogenic needles. The nonechogenic needles were scoring poorly either with or without beam steering. It didn’t really improve things very much.”
At 40 degrees, the nonechogenic needle scores improved from poor to good with medium and steep beam steering; the echogenic needle scores improved from intermediate to good with steep beam steering. At 50 degrees, the echogenic needles had good scores with or without beam steering. At 60 degrees, the echogenic needle scores improved from intermediate to good with steep beam steering.
These data will help to improve needle visualization at moderate angles of insertion, according to the researchers.
The findings were presented at the 2016 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 1447).